Electrical discharge device



Oct. 26, 1948. KATHER ELECTRICAL DISCHARGE DEVICE 2 Sheets-Sheet 1 FiledJuly 20, 1944 /r If! I m I11 I r Oct. 26, 1948. E. N. KATHER 1 2,452,056

' ELECTRICAL DISCHARGE DEVICE Filed July 20, 1944 2 Sheets-Sheet 2Patented Oct. 26, 1948 2,452,056 ELECTRICAL DISCHARGE DEVICE Erich NevinKather, South Lincoln, Mass, as-

signor to Raytheon Manufacturing Company, Newton, Mass, a corporation ofDelaware Application July 20, 1944, Serial No. 545,768

Claims. 1

This invention relates to an electron discharge tube of the type adaptedto generate ultra high frequency oscillations, and more particularly toone in which the frequency of one or more resonant circuits within thetube determines the fre quency of the oscillations produced.

In such devices it is frequently desirable to vary, within limits, thefrequency of the oscillations generated by the tube.

It is among the objects of this invention to provide a novel andeificient means for varying the frequency of the oscillations generatedby the tube while the tube is in operation. In such devices variousfactors beyond the control of the operator may alter the frequency atwhich the tube is resonant. For example. a change in the operatingtemperature may alter the resonant frequency.

A further object of the invention is to provide a means for varying thefrequency of the oscillations generated by the tube which will alsofunction as a frequency stabilizer .to maintain the oscillationsgenerated at the desired adjusted frequency regardless of changes in theoperating 7 conditions.

The above and other objects of the invention will be fully set forth inthe following detailed description, taken in conjunction with theaccompanying drawings in which:

Fig. 1 shows a transverse section through a magnetron constructed inaccordance with my invention;

Fig. 2 shows a section taken on line 2-2 of Fig. l; and

Fig. 3 shows a partial side elevation, partial section taken on line 3-3of Fig. 2.

Referring to the drawings, there is shown a magnetron comprising a blockI of conductive material, such as copper. A plurality of anode arms 2project radially from the interior surface of the block I providingtherebetween a plurality of resonant cavities 3. Hollow end sections 4and 5 covered by end caps 6 and I are provided at each end of the blockI. A cathode 8 is provided centrally of block I adjacent the inner endsof the anode arms 2 and is supported by lead-in conductors 9 and I llextending through the hollow end sections 4 and 5. Lead-in conductors 9and III are sealed in glass seals I I and I2 mounted at the outer endsof conductive pipes l3 and I I, respectively. The conductive pipes I3and [4 are hermetically secured within the wall of the block I adjacentthe end sections 4 and 5. Within one of the resonant cavities 3 is acoupling loop I5 having one end connected to a lead wire IS. The

lead wire I6 is sea-led through a glass seal II mounted at the outer endof a conductive pi-pe I8 hermetically secured within the wall of theblock I. The other end of the coupling loop I5 is secured to the innerend of the conductive pipe I8. Magnetic poles l9 and 20 are providedadjacent the end caps 6 and I to create a magnetic field extendinglongitudinally of the device.

When such devices are energized, oscillations are set up from whichenergy may be derived by the coupling loop I5 and led out of the tube bylead wire I6 and conductive pipe I8 which constitute a coaxialtransmission line. On the exterior of the tube the high frequencyoscillations may be conducted to any suitable utilization circuit by acontinuation of the concentric line or any other transmission line in amanner known in the art.

In the operation of such devices a capacity exists between the cathode 8and the face of each of the anode arms 2. Also capacitances existbetween the side walls of adjacent anode arms 2. The interior walls ofthe resonant cavities 3 constitute inductances. The anode is so designedand spaced relative to the cathode that the capacitances and inductancesdescribed constitute circuits which are tuned. The construction so faidescribed is such that these circuits are resonant at a predeterminedfrequency depending upon the geometry of the tube. The device isintended to operate so that each cavity 3 forms a circuit tuned to thefrequency at which each of the other cavities 3 oscillates.

In order to vary the frequencies of the oscillations generated by thetube, I provide a coupling loop 2| extending into the end sectioniclosely adjacent to one end of one of the cavities 3. One end of theloop 2| is connected to the inner end of an outer tubular conductor 22of a section of coaxial line 23 having an inner conductor 24. The otherend of the loop 2| is connected to said inner conductor 24. The outerend of the coaxial line 23 is closed and the line is supported near itsinner ends by a flexible diaphragm 25, which diaphragm has a centralopening through which the outer tubular conductor extends and in whichit is hermetically sealed. The diaphragm 25 is soldered or otherwiseintegrally connected along its peripheral edge to therim of a cup-shapedmember 21, the joint constitutin an hermetic seal. The cup-shaped member21 is mounted upon one end of the block I, a portionof the block I beingcut away for this purpose, and the cupshaped member soldered orotherwise secured to the side wall of the block I in a manner to securean hermetic seal therewith. An elongated opening 28 is provided in thebase of the cup-shaped member through which a reduced end 29 of theouter tubular conductor 22 extends. The dimensions of the elongatedopening 28 are such that the inner end 29 of the outertubular conductor22 may be moved upwardly and downwardly within the opening.

The length of the coaxial line 23 is fixed to give a predeterminedreactance as determined by the tube and load characteristics. Thislength is such that the coaxial line is approximately resonant at theoperating wave length but nevertheless; ofi to one side at resonance.The length may be taken either side of resonance dependingon the tubeand load characteristics, in the one case the reactance of the coaxialline will be inductive and in the other case its reactance willxbecapacitive. In either case the line 23 constitutes a reactance coupledin the oscillatory circuit of the tube by the loop 2|. By applyingpressure to the outer end-.of the coaxial line 23,'the coupling loop 2|may be moved relative to the resonant cavity 3, the diaphragm 25 flexingfor this purpose, so that the loop-will be'closer toor farther from theoscillatory field of thislcavity and therebythe coupling between thecoaxial line and the resonant cavity. may be varied. An increase incoupling caused bymoving the'loop 2| closer to the rasonantcavity 3:increases the amount of the reaotance: coupled in the. oscillatorycircuit. Movement of the loop in this direction changes the-frequency atwhich: thecircuitprovided by the "system is resonant; Byamoving the loopfarthenfromi the. cavity, the coupling therebetween isdecreasedand-ithe. resonant frequency of the system is accordinglychanged. Breferably therratioof the inner diameter of the outertubular'conductor to the outer diameter ohtheijinnenconductor ismadeequal to 3.6. In other wordsv these parts are dimensioned toprov-ide:a1high Q and? since the. coaxial line is approximately resonantat the operating wave lengthbut neverthelessoff to one side atresonance, that-istheresonantirequency of the eoax-iab line is slightly:different from the resonant frequency-of the system, the line will tendto pull the system back totheadjusted frequency wheneventhe systemtendsto vary from the predetermined frequency. Thusthe device provides bothatuning= means and a'means for stabilizing the frequency'of the. system.

From the above description it will be seen that th'elnventi'onprovidesanovel and eflicient means f onvaryingawithin limits. thefrequencies of the oscillations'generated by the tube at the will oftheoperator while. the tube is in operation. Furthermore, where theinductively coupled line is made approximately resonant at the operatingwave lengthof the.tube but nevertheless off to one side at resonance,the invention provides a frequency stabilizing. effect at the adjustedfrequency;

While there has been herein described an illustrativeembodiment oi theinvention, other embodiments within the scope of the appendedclaimszwill beapparent to those skilled in the art from a considerationof the embodiment shownand the-teachings hereof. For example,the-invention maybe applied to tubes of the type having a resonantcavity determining the frequency of the oscillations produced other thanthe specific -mag-netron shown. The-coupling loop may be made adjustablerelative to the resonant cavity by--means other than the specific meansshown-and the circuit prltividing'the reactance connected to theadjustable coupling need not necessarily be a coaxial line.

What is claimed is:

1. A magnetron comprising: an evacuated envelope, electrode elementswithin said envelope providing a resonant circuit, a coaxial line havingone end thereof opening into said envelope and the other end thereofhermetically sealed, a coupling loop coupling said coaxial line to saidresonant circuit, and means carried by said envelope and adjustablysupporting said coaxial line to enable-the movement of said couplingloop relative to said resonant circuit to vary the inductive couplingtherebetween.

2. 'A magnetron comprising: an evacuated envelope, electrode elementswithin said envelope providing a resonant circuit, a. coaxial lineincluding an outer tubular conductor and an inner coaxial conductor, oneend of said outer tubular conductor opening into said envelope and theothenend; thereof being hermetically sealed, a coupling. loop connectedat one end to said outer tubularconductor andat its opposite end to saidinner conductor and extending into said envelope coupling said coaxialline to said resonant circuit, and means carried-by said envelope andadjustably supporting said coaxial lineto enable the movement thereof tothereby movesaid coupling loop relative to said resonantcircuit to varythe inductive coupling therebetween.

3. A magnetron comprising: an evacuated en-v velope, electrode elementswithin said envelope providing a resonant circuit, a coaxial lineincluding an outer tubular conductor and an inner coaxial conductor, oneendof said outer tubular conductor opening into said envelope and theother end thereof being hermetically sealed, a coupling loop connectedat one'end to said outer tubular conductor and at its oppqsite end tosaid inner conductor and extending into said envelope coupling saidcoaxial line to said resonant circuit, said coaxial line being movablymounted and hermetically sealed in a wall of said envelope wherebysaidcoupling loop is. movable relative to said resonant circuit to vary theinductive. coupling therebetweem 4. A magnetron comprising: an evacuatedenvelope, electrode elements within said envelope providing a resonantcircuit, a coaxial linehaving one end thereofopening into said envelopeand the other end thereof hermeticallysealed, said coaxial line beingapproximately tuned to the frequency ot'said resonant circuit, acoupling loop coupling said coaxial line to said resonant circuit, andmeans carried by said envelope and adjustably supporting said coaxiallineto enable the movement of said coupling loop relative tosaidresonant circuit to vary the inductive coupling therebetween.

5; A- magnetron comprising: an evacuated envelope; electrode elementswithin said envelope providing a, resonant circuit, a coaxial lineincluding an outer tubular conductor and an inner coaxial conductor, oneend of said outer tubular conductor opening into said envelope and theother end thereof being hermetically sealed, a coupling loop connected;at one end to said outer tubular conductor and at its-opposite end tosaid inner conductorand extending into said envelope couplingsaidcoaxial line to said resonant circuit, saidcoaxial line beingapproximately tuned to the frequency of said resonant circuit andmovably mounted and hermetically sealed in a wall of said envelope tothereby enable the movement of said coupling loop relative to saidresonant circuit to vary the inductive coupling therebetween.

6. An electron discharge device comprising: an evacuated enveloped,electrode elements within said envelope providing a resonant circuit, acircuit separate from said electrode elements providing a reactance, acoupling loop carried by said reactance circuit and extending into saidenvelope, in spaced relationship to said resonant circuit, forinductively coupling said resonant and reactance circuits, and meanscarried by said envelope and adjustably supporting said reactancecircuit to enable variation of the spacing between said coupling loopand said resonant circuit for varying the coupling therebetween.

7. An electron discharge device comprising: an evacuated envelope,electrode elements within said envelope providing a resonant circuit, acircuit separate from said electrode elements approximately tuned to thefrequency of said resonant circuit and providing a reactance, a couplingloop carried by said reactance circuit and extending into said envelope,in spaced relationship to said resonant circuit, for inductivelycoupling said resonant and reactance circuits, and means carried by saidenvelope and adjustably supporting said reactance circuit to enablevariation of the spacing between said coupling loop and said resonantcircuit for varying the coupling therebetween.

8. An electron discharge device comprising: an evacuated envelope,electrode elements within said envelope providing a resonant circuit, acoaxial line having one end thereof opening into said envelope andapproximately tuned to the frequency of said resonant circuit but off toone side at resonance providing a reactance, a coupling loop carried bysaid coaxial line and extending into said envelope, in spacedrelationship to said resonant circuit for inductively coupling saidresonant circuit and said coaxial line, and means carried by saidenvelope and adjustably supporting said coaxial line to enable variationof the spacing between said coupling loop and said resonant circuit forvarying the coupling therebetween.

9. An electron discharge device comprising: an evacuated envelope,electrode elements within said envelope providing a resonant circuit, acoaxial line having one end opening into said envelope and the other endhermetically sealed and approximately tuned to the frequency of saidresonant circuit but off to one side at resonance providing a reactance,a coupling loop inductively coupling said resonant circuit and saidcoaxial line, a flexible diaphragm mounted in a wall of said envelopeand hermetically sealed therewith, said coaxial line being sealed in anopening through said diaphragm whereby movements of said line vary thespacing between said coupling loop and said resonant circuit for varyingthe coupling therebetween.

ERICH NEVIN KATHER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,233,166 Hahn Feb. 25, 19412,242,249 Varian et a1. May 20, 1941 2,243,537 Ryan May 27, 19412,304,186 Litton Dec. 8, 1942 2,311,520 Clifford Feb. 16, 1943 2,348,986Linder May 16, 1944 2,404,086 Okress July 16, 1946 2,404,279 Dow July16, 1946 2,408,235 Spencer Sept. 24, 1946

